1. Field of the Invention
The present invention relates generally to power management in a system comprising a plurality of computers. More particularly, the present invention relates to changing the power state of one or more computers in the system based on a change in demand for the processing capability of the system or in accordance with criteria specified by a user.
2. Background of the Invention
As is well known, a computer can execute a software application to perform virtually any desired function. As is also known, processing capability can be increased by networking together more than one computer. Each computer in the network then can be assigned one or more tasks to perform. By having a plurality of computers working in concert with each computer performing a portion of the overall set of tasks, the productivity of such a system is much greater than if only one computer was forced to perform the same set of tasks.
Computers, of course, require electrical power to operate and, as a result, generate heat. Despite attempts to reduce the electrical current draw and heat generation by computers, computers today generally draw more electrical power and generate more heat than previous generations of computers. Networks of computers may require very substantial amounts of electrical power and which may cause a great deal of heat to be generated. The electrical power required to power computers is, of course, not free of charge and, at times, may carry a very substantial cost. The heat generated, particularly by networks of computers, may also be very substantial and, if not removed from the system, may damage the computers. There is an additional cost associated with the cost of the electrical power required for the cooling systems necessary to remove the heat from the computers. The amount of power required for cooling is proportional to the amount of heat that must be removed. Thus, all else being equal, any reduction in the electrical current draw by a computer or network of computers is highly desirable.
One relatively recent advancement in the area of power management involves an individual computer being able to monitor its level of activity and transition itself to a reduced power consumption mode of operation during periods of low activity. For example, if no input, such as from a keyboard, mouse, disk drive, or a network connection, has been received for a certain amount of time, the computer may take action to reduce its power consumption. One response to such a low level of activity might be turn off all disk drives within the computer or to clock one or more of the computer's microprocessor at a reduced frequency.
Although helpful in managing power consumption on an individual computer basis, this type of methodology may not be the most efficient technique to manage power in a network of computers. Accordingly, any improvement that can be made in the area of computer power management is highly desirable.